Q. Atomic radii of $Ti$, $Zr$ and $Hf$ vary
A) $Ti\ > Zr > Hf$
B) $Ti\ < Zr < \ Hf$
C) $Ti < Hf < Zr$
D) $Ti < Zr = HF$
Explanation
(d)
Ti, Zr and Hf belong to IV B group of Periodic Table and in a group atomic radii increases on moving down. However, the transition metals of $4d$-series have nearly the same radii as metals of $5d$-series. Hence the order of atomic radii is
$Ti < Zr \approx HF\$
Due to nearly equal atomic radii, Zr and Hf are called chemical twins.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.